CITY lost ground to rivals Chesterfield in the play-off scramble to leave Phil Parkinson cursing: One mistake cost us.

A blunder from Gary MacKenzie, whose header back to keeper Ben Williams fell short, allowed Byron Harrison to score the only goal in a dour contest at Valley Parade last night.

City would have shot up to sixth with a win but instead it is the visitors sitting pretty in the final League One play-off spot.

Parkinson admitted: "It was a game typical of this stage of the season. There was a lot at stake and no quarter given.

"They came and matched up our diamond in the midfield area and made it difficult. There was nothing in the game but one mistake has cost us.

"It's a shame really. Obviously we weren't as good as we played on Saturday – but it wasn't like a 20 per cent dip, it was more five or ten per cent in the first half.

"You've got to give Chesterfield credit for that as well. Once they got the goal, they became very difficult to break down."

Parkinson refused to blame on-loan Blackpool defender MacKenzie, who was deputising for hamstring victim Andrew Davies.

The City boss said: "Gaz has been tremendous for us and I didn't take him off because of that. I took him off because I thought he looked fatigued towards the end of the game.

"But we spoke before the game about keep playing forward. We told the defenders it's not the conditions to go back to the keeper unless your distances are right.

"The conditions were very tough and Chesterfield hung on to their lead very well. But neither keeper was tested much in the whole game.

"It was very tight, which is just how I expected it to be. You've got to stay in the game and have the ability to try and grind out a result.

"I'm sure if we hadn't made that mistake, we've have had at least a point."

City's best chance fell to substitute Tony McMahon late on but his close-range shot was superbly kept out by Tommy Lee, the Keighley-born goalkeeper who played for the Bantams as a child.

Parkinson said: "It was a great chance and a good save by the keeper. But those are the key moments in a game.

"The blow was letting the goal in just before half-time. If we had got in at 0-0, I would have fancied us to go on and win it.

"But you've got to give Chesterfield credit for the way they played. They were committed in their defending and made it very difficult for us.

"It's a setback for us but we move on quickly to Doncaster away on Friday."